On Mon, 1 Jan 2007, Feng Qiu wrote:
Hi Duncan:
Thank you very much! I checked out unique(), it does exactly what
I
want. But I'm still curious about if R provides "STL"(standard template
library).
No.
Some things the STL does aren't needed in R, others are implemented
differently, and others aren't implemented.
One particularly important example is iterators, which will often either
happen invisibly due to vectorized operations or will be done with the
*apply family of functions.
Your example could have been done either way. Using duplicated() is the
vectorized approach; the apply approach would use tapply().
C++ is not terribly similar to R. A lot of the effort in STL is expended
on allowing a piece of code to be used on different types (where
appropriate). In R you have to expend effort on stopping a piece of code
being used on different types (where inappropriate).
-thomas
Thomas Lumley Assoc. Professor, Biostatistics
tlumley at u.washington.edu University of Washington, Seattle